KR19980702557A - Voice messaging system and method using the orthogonal modulation component efficiently - Google Patents

Abstract

A modulation scheme (600) useful in a voice paging system wherein both of the two orthogonal modulation components (500 and 510) are used to carry a single voice message to the receiver or two halves of two separate messages for the receiver. A single voice message is transmitted in half the time.

Description

Voice messaging system and method using the orthogonal modulation component efficiently

In radio frequency (RF) communication systems suitable for transmitting voice messages to other receivers, such as a portable device or a selective calling receiver (i.e., a pager), single sideband modulation techniques are used due to spectral efficiency. Currently, only one upper or lower side wave is used to carry information to another receiver. Demodulation and reconstruction of a message that is entirely carried over to the upper or lower side demodulator is such that during the duration of a message on the channel the receiver samples both the in-phase (I) component and the quadrature (Q) component of the signal . Both side waves are restored, but the message is limited to only one of the side waves. Information in other side waves is discarded.

The fact that only one sideband carries the message results in inefficient use of air time resulting in traffic inefficiency on the allocated RF band. Moreover, this leads to inefficient use of the receiver processing capability, and inevitably consumes the energy of the battery in the portable receiver device.

The present invention relates to a paging system, and more particularly, to a speech paging system and method using components in an orthogonal modulation scheme.

1 is a diagram of a selective-paging communication system according to the present invention.

2 is a diagram showing a subchannel spectrum according to the present invention.

3 is a block diagram of a transmitter in accordance with the present invention;

Figure 4 is a diagram of an amplitude compander module of a transmitter according to the present invention.

5 is a block diagram of one orthogonal modulator in accordance with the present invention.

6 is a block diagram of another orthogonal modulator in accordance with the present invention;

7 is a diagram showing the impulse response of a Hilbert filter according to the present invention.

8 is a polyphase diagram of interpolation modulation of a transmitter according to the present invention.

9 is a diagram showing the impulse response of the interpolation filter in interpolation modulation.

10 is a block diagram illustrating the use of a time reverser module of a transmitter in accordance with the present invention;

11 is a plot showing a voice message.

12 is a diagram showing the digital representation of the voice message shown in FIG.

Figures 13 and 14 are diagrams illustrating digital representations of two half of the voice message of Figure 11;

15 to 17 are timing charts showing an example of a signaling protocol according to the present invention.

18 is a block diagram of a receiver in accordance with the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to Figure 1, an electrical block diagram of a wireless communication system 100 is shown in accordance with a preferred embodiment of the present invention. The wireless communication system 100 is connected to the system controller 102 via a conventional packet switched telephone network (PSTN) 108 by a conventional telephone 101, a fax machine 120 or a conventional telephone link 110 And a message input device such as a messaging terminal 122. The system controller 102 is typically a twisted pair of telephone lines and is coupled to a plurality of radio frequency transmitters / receivers 103 (not shown) via one or more communication links 116 that may additionally include RF, microwave, ). The system controller 102 encodes and decodes the inbound and outbound telephone addresses in a format compatible with the land line message switch computer. The system controller 102 also includes a plurality of select paging receivers 106, also referred to as selective call radios, which indicate as radio frequency transmitters / receivers 103 that these devices have transmit or acknowledge back- And encodes and schedules outbound messages, which may include information such as analog voice messages, digital numeric messages, and response commands, for transmission. The system controller 102 functions to decode an inbound message including an unsolicited response message received by the radio frequency transmitter / receiver 103 from a plurality of selective paging receivers 106 incidentally.

An example of a response message is an acknowledgment and a specified response message. The acknowledgment is a response to the outbound message initiated by the system controller 102. An example of an outbound pneumatic message for the selective paging receiver 106 is a paging message entered from the phone 101. An example of an outbound analog message for selective call receiver 106 is a voice page message entered from telephone 101. [ In these instances, the acknowledgment indicates successful reception of an outbound pneumatic or analog message. The designated response message is a message transmitted from the selective paging receiver in response to the command included in the outbound message from the system controller 102. An example of the designated response message is a message initiated by the selective call receiver 106, but it is only transmitted after the designated response command is received from the system controller 102. [ In contrast, the designated response command is communicated by the system controller 102 after the inbound message request permission to send the designated response message is communicated from the selective-paging receiver 106 to the system controller 102. The response message is preferably sent at the time specified in the outbound message or command, but may optionally be transmitted using an unscheduled protocol such as the ALOHA or the slotted ALOHA protocol well known to those skilled in the art. The unsolicited message is an inbound message sent by the selective call receiver 106 without having to receive an outbound message that requires a response. An example of an unsolicited message is an inbound message from a selective paging receiver 106 that alerts the wireless communication system 100 that the selective paging receiver 106 is within the wireless range of the wireless communication system 100. An unsolicited message may include a request to send a specified response, and may include data such as pneumatic data. Unsolicited messages may be transmitted using ALOHA or the slotted ALOHA protocol. The inbound and outbound messages are included in the outbound radio signal transmitted from the conventional antenna 104 coupled to the radio frequency transmitter / receiver 103 and the inbound radio signal received thereby. Wireless communication system 100 may also be configured such that each fixed site includes a system controller 102, a radio frequency transmitter / transmitter 103, a system controller 102 to a radio frequency transmitter / And a plurality of fixed sites 115 having an antenna 104. The antenna 110 is a wireless communications device,

The system controller 102 may be a conventional hybrid cellular, simulcast, satellite or multiple radio frequency transmitter / receiver 103, a conventional antenna (not shown) to provide a reliable radio signal within the geographical region of the world, Lt; RTI ID = 0.0 > 104, < / RTI >

Each paging receiver 106 assigned for use in the wireless communication system 100 has at least one address to which a unique paging address is assigned. The selective calling address enables the message from the system controller 102 to be transmitted only to the selective calling receiver 106 to which it is addressed.

According to the present invention, a voice message is transmitted on one of a plurality of subchannels. Figure 2 shows one subchannel. In a preferred embodiment, there are three subchannels in a radio frequency (RF) channel, and the RF channel has a width of, for example, 25 kHz. Optionally, seven subchannels of a 50 kHz channel may be used, and one of ordinary skill in the art will appreciate that a different number of subchannels may be used depending on the bandwidth of the channel. The subchannels are separated by 6250 Hz. Each subchannel has an upper side wave (500), a lower side wave (510), and a pilot carrier (520). As will be apparent from the following discussion, side waves 500 and 510 are used to carry a single message or a portion of two separate messages. The spectrum allocation for voice in one subchannel is 2500 Hz, which includes a voice bandwidth of 300 to 2800 Hz.

FIG. 3 illustrates a transmission process 600 in accordance with the present invention in which messages, particularly analog voice messages, are transmitted. This process is preferably performed by the transmitter / receiver 103, but is optionally performed by the system controller 102. In any case, the ultimately transmitted information is integrated into the signaling protocol, which will be described below in conjunction with Figs. 15-17.

The incoming speech message S (n) is received via the telephone line, for example, by the system controller 102. For example, if the telephone line is a T1 line, then the voice is encoded using a 64 kbps pulse code modulation (CPM), which is converted to a linear 16 bit PCM with an 8 kHz sampling rate by an A / D converter 605. Regardless of the type, the voice message on the conventional analog phone line is converted into a suitable digital format by the A / D converter 605. Next, the digital voice information is processed by a band-pass filter (BPF) 610 that filters out frequencies that are outside the typical voice spectrum of 300-2800 Hz. The filtered digital voice information may then be subjected to automatic gain control (AGC) to compensate for variations in the amplitude of the input voice, such as variations that occur when a person speaks with a handset such as a telephone, a cordless telephone, Gt; module 620. < / RTI > AGC module 620 improves intelligence and also ensures that the added pilot carrier energy is always less than a fraction of the signal energy present in the transmitted signal. For example, an AGC scheme with a fast attack time constant of 2.5 microseconds and a slow decay time constant of, for example, 2 sec, maintains the speech energy constant in a wide range of speech samples without distorting speech characteristics. . These parameters are not used in a limiting sense.

The digital voice information is then the time-annular amount compressed by the time-to-date compressor 630. Any number of time-conversion compression schemes are useful. Next, the digital voice information is passed through an amplitude compressor 640, which compresses at a rate of about 2: 1, for example, to prevent channel noise.

An orthogonal modulation scheme with first and second orthogonal modulation components is used. According to one embodiment of the present invention, the first and second orthogonal modulation components are used to carry a segment of a single voice message. According to another embodiment, the first and second orthogonal modulation components are used to carry the first and second separate voice messages. In either embodiment, the first and second quadrature modulation components are, for example, upper and lower side loudspeakers 500 and 510, respectively, or in phase (I) and quadrature (Q) components (also referred to as channels) . Moreover, whichever scheme is used, the present invention is contemplated to orthogonally modulate the first and second quadrature components into the first and second message portions, respectively, to generate the first and second quadrature modulation components.

The voice splitter module 650 is used when a single message is to be carried by both the first and second orthogonal modulation components. The output of the speech divider module 650 is a portion of the first and second voice messages having the speech signal S (n) in time. The voice message portions are referred to as Sa (n) and Sb (n), respectively. However, if two separate messages are to be modulated with the first and second orthogonal modulation components, the voice divider module 650 is not used and the two voice messages S1 (n) and S2 (n) Are each processed in parallel by modules 600-640 (similar to modules 600-640 not shown) before proceeding.

A single voice message S (n) is temporally divided into first and second message portions Sa (n) and Sb (n) by a voice divider module 650. In the case of digital information, the speech divider module 650 may include a numeric table representing the processed voice message S (n) at the same point as the zero crossing or other convenient temporal occurrence anywhere near the temporal midpoint of the voice message S (n) .

Next, the voice message portions Sa (n) and Sb (n) (or voice messages S1 (n) and S2 (n), as the case may be) are orthogonal modulators for modulating voice message portions into first and second orthogonal modulation components (660). The orthogonal modulator 660 is described in detail later.

The pilot carrier is then added to the output of quadrature modulator 660 by adder 705. [ The pilot carrier has a maximum amplitude of amplitude x voice information of about 0.15.

Prior to this point in the transmitter processing, the module operates with a sampling rate of, for example, 8 kHz. When this is ultimately converted into analog information, the image occurs in multiples of 8 kHz. To remove such an image, a reverse-imaging filter can be used. As a result, in order to avoid such a necessity, the processed signal is interpolated by the interpolator module 71 at a sampling rate of 16 kHz, and the image is separated into 16 kHz. Once converted to analog information, the analog filter is used to remove the image.

The output of the interpolator is then converted from digital to analog using a 16-bit D / A converter module 720. The analog output of the D / A converter module 720 then passes through an appropriate analog reconstruction (de-imaging) filter 730 to remove all the images leaving only the baseband SSB signal.

The quadrature amplitude (QAM) modulation module 740 is coupled to the output of the reconstruction filter 730 to modulate the SSB signal into an appropriate subchannel for transmission via the antenna 750. [

4 shows the amplitude multiplier module 640 in detail. As is known in the art, amplitude compression includes boosting the low amplitude component of the signal and compressing the high amplitude of the signal. This protects the low-amplitude components from the effects of any channel noise, providing better intelligence and quality.

Amplitude compressing unit 640 generates the control voltage factor c2 (n) by calculating the average absolute value of the signal averaged over N samples. This is accomplished using two moving average filters. The first moving average filter 641 calculates the average absolute value of the N input samples and the second moving average filter 642 calculates the N sample average of the average absolute value obtained from the output of the first moving average filter 641 .

In delay module 643, the input signal is delayed by N-1 samples and the output amplitude confinement signal is calculated by (delayed sample X compressor gain factor) / (control voltage c2 (n)) ^1/2 .

In the implementation shown in Figure C, N = 48 and gain factor = 0.140625XN. Preferably and not shown in FIG. 4, the amplitude confinement signal is bandpass filtered again by a 300-2800 Hz bandpass filter to remove harmonics that may have been introduced into the confusion. A filter similar to the BPF 610 may be used.

FIGS. 5 and 6 illustrate two examples of implementations of orthogonal modulator 660. FIG. In FIG. 5, the voice message portion modulates the upper and lower side waves while the voice message portion in FIG. 6 modulates the I and Q components.

5, the orthogonal modulator 660 includes first and second Hilbert transform modules 670 and 680, respectively. The Hilbert transform modules 670 and 680 each include 33-tap Hilbert filters 672 and 682, 16-sample delay modules 674 and 684, respectively, and multipliers 676 and 686, respectively. The 33-tap Hilbert filters 672 and 682 generate a Q component and the 16-sample delay modules 674 and 684 generate an I component. The multipliers 676 and 686 generate a 90 degree phase shift as required for the Q component. The upper side lobe I + j ^* Q is generated by the summer 685 and the lower side lobe Ij ^* Q is generated by the summer 695.

On the other hand, in Fig. 6, another configuration of the orthogonal modulator is shown at 660 '. In this configuration, the quadrature modulator 660 'includes a delay module 700 similar to the delay module 674 and a Hilbert filter 701 similar to the filter 672. The voice message portion Sa (n) (or S1 (n)) passes through the delay module 700 and the voice message portion Sb (n) (or S1 (n)) passes through the Hilbert filter 701. The output of the Hilbert filter is coupled to multiplier 702 during a 90 degree phase shift. At summer 703, the output of the delay module 700 is added to the output of the multiplier 702. As such, the output of the summer 703 may be a message portion Sa (n) modulated with an I component and a message portion Sb (n) modulated with a Q component or, in the case of the second embodiment, a message portion S1 n) and a message part S2 (n) modulated with a Q component.

7 shows the appropriate impulse response of the 33-tap Hilbert filters 672, 682 and 701 as an example.

FIG. 8 is a polyphase representation of an example of a suitable interpolator module 710 known in the art, and FIG. 9 is an impulse response of the interpolator module 710. As shown in FIG. 9, all the alternative samples are zero, which reduces computational complexity. In addition, the frequency response of the filter has a band pass at 0-3 kHz and 60 dB at 5,600 Hz. In FIG. 8, H ₀ (z ² ) = h ₀ + z ^-1 h ₂ + z ^-2 h ₄ + ...,; And H ₁ = z ^-1 [h ₁ + z ^-1 h ₃ + z ^-2 h ₅ + ...]. Taking the advantage of alternating zeros in the impulse response and polyphase representation, the operation is performed at 16 kHz sampling rate for one channel (I or Q) substantially improved by more than 21 times per sample at 16 kHz in the direct implementation 6 times.

Optionally, the time reversal occurs before any message portion, one or more message portions, are modulated by orthogonal modulator 660 (or 660 '). 10 shows an optional time reversal module 660 coupled to the output of the speech divider 650 when a single message is transmitted and to the output of the amplitude compensator 640 when two separate message portions are transmitted. The time reversal module 800 reverses the message portion in time to be transmitted in a time reversed manner. In the digital implementation of the present invention, the time reversal module 800 reads a sequence of numbers from the output of the speech divider 650 or the amplitude decompressor 640 in the first-to-last-first order. For example, the time reversal module 650 is a software counter that decreases from the highest index downward as described below.

By time reversing the message portion, the transmitted voice information is scrambled and therefore the secret or privacy rating is low in that the time reversed portion of the voice signal can not be readable or intelligent at the receiver, which often monitors the channel. As such, the transmitted signal can be demodulated and intelligent only for receivers that knowingly know that the transmitted voice information is time reversed. The determination of whether to time invert or not to invert time may be made within the signaling protocol on the frame based on a frame based on a pre-aligned sequence known to the transmitter and receiver. One example of a sequence known to both the transmitter and the receiver is the binary encode address of the selective call receiver. Moreover, when I and Q channels are modulated, the simultaneous superposition of the spectra in the channels of the two voice portions with time reversal of one or both time makes the intelligence to the impromptu monitoring receiver opaque.

Referring to Figs. 11 to 14, an example of transmitting a voice message according to the present invention will be described. As shown in FIG. 11, the voice message Vm is shown to have a time duration of Tm. Once sampled and digitized by the A / D conversion module 605, the voice message S (n) is defined as a sequence of digital digits 1 through N, which is the digital representation of the sample shown in FIG. The digital representation of the voice message Vm is divided into two parts by the voice divider 650. The preferred point of isolating the voice message is the zero point at time Ts. Thus, the digital value of sample k is the value of the voice message at time Ts. 13 and 14, the first message part Sa (n) includes digital values for samples 1 through k, and the second message part Sb (n) includes digital values for samples k + 1 through N Respectively. Either or both of the first and second message portions are optionally time reversed and the parentheses in Figures 13 and 14 indicate the order of the digital values when each message portion is time reversed.

If upper and lower side loudspeakers 500 and 510 are used to carry the message part, upper side loudspeakers 500 are formed as one of the message parts, such as the first part, using the Hilbert transform module 670. The upper side lobe carrying the first message part is represented by ISa + jQSa. Similarly, the lower side ladder that carries the second message portion (time reversed or not) is represented by ISb-jQSb generated by the Hilbert Transformation module 680. 2, the first and second message parts Sa (n) and Sb (n) are carried by upper and lower side waves 500 and 510, respectively. As a result, the voice message having the duration Tm is transmitted in half the time because half of the message is carried by the upper side loudspeakers 500 and the other half is carried by the lower side loudspeakers 510. [

As will become clear from the following description, when the receiver uses digital signal processing but ignores one of the side waves, the receiver normally detects both side waves. If the message is time compressed at startup, both side waves are used to transmit the message in half of the transmission or air time. Moreover, since the receiver receives the same message in half the time, the power consumption decoding circuit consumes less power because it is only activated for half the time.

Similarly, the upper and lower side waves 500 and 510 optionally carry two separate messages. In this case, at the output of each of the Hilbert transform modules 670 and 680, the message 1 S1 (n) is represented as I _S1 + jQ _S1 , and the message 2 S2 (n) is represented as I _S2 -jQ _S2 .

In the case of the paging system, the voice message part is transmitted according to the protocol. One such protocol is shown in Figures 15-17. Referring to FIG. 15, there is shown an exemplary feature of an example of a transmission coding format of an outbound signaling protocol used by the wireless communication system 100 of FIG. 1, and details of a control frame 330, in accordance with a preferred embodiment of the present invention, Is shown. The control frame 330 is also classified as a digital frame 330.

The signaling protocol is subdivided into protocol divisions, which are time 310, cycle 320, frame 330, block 340, and word 350. Uniquely identified cycles up to 15 orthogonal are transmitted at each time 310. Typically, all 15 cycles (320) are transmitted every hour. A unique identified frame is transmitted in each cycle 320, including a control frame 330 and an analog frame 430 (described below with reference to FIG. 8) up to 128 1.875. Typically, all 128 frames are transmitted. 115 milliseconds and 11 160 milliseconds. A single sync and frame information signal 331, which continues the uniquely identified block 340, is transmitted in each control frame 330. [ A bit rate of 3200 bits per second (bps) or 6400 bps is available during each control frame 330. The bit rate during each control frame 330 is communicated to the selective paging receiver 106 during the synchronization signal 331. When the bit rate is 3200 bps, as shown in FIG. 6, 16 uniquely identified 32 bit rates are included in each block 340. When the bit rate is 6400 bps, 32 uniquely identified 32-bit words (not shown) are included in each block 340. In each 32-bit word, in a manner known to those skilled in the art, at least 11 bits are used for error detection and less than 21 bits are used for the information. The bits and words 350 in each block 340 are transmitted in an interleaved manner using techniques known to those skilled in the art to improve the error correction capability of the protocol.

The information includes frame structure information in the block information field (BI) 332, one or more selected paging addresses in the address field (AF) 333, and one or more vectors in the vector field (VF) Are included in each control frame 330 in the information field. The vector field 334 starts at the vector boundary 334. Each vector in the vector field 334 corresponds to one of the addresses in the address field 333. The boundaries of the information fields 332, 333 and 334 correspond to the types of system information included in the synchronization and frame information field 331, the number of addresses included in the address field 333, Variable information fields 332 and information fields 332, 333, and 334, depending on factors such as the number and type of fields.

Referring to FIG. 16, there is shown a diagram of a transmission format of an outbound signaling protocol used by the wireless communication system of FIG. 1, and a timing diagram including details of a voice frame 430, in accordance with a preferred embodiment of the present invention. Are shown. The voice frame 430 is also classified as an analog frame 430 below. The duration of the protocol division time 310, cycle 320, and frames 330 and 340 are the same as those described for the control frame of FIG. Each analog frame 430 has a header portion 435 and an analog portion 440. The information in the synchronization and frame information signal 331 is the same as the synchronization signal 331 in the control frame 330. [ As described, the header portion 435 of the frame 430 is frequency modulated and the analog portion 440 is amplitude modulated. The analog portion 440 is the portion that carries the voice message over one of the orthogonal modulation components. 16 illustrates that the wireless communication system includes three subchannels, i.e., each subchannel is similar to that shown in FIG. 1 and has a pilot subcarrier that can be assigned a voice message portion for transmission.

According to a preferred embodiment of the present invention, the transition portion 444 comprises amplitude modulated pilot subcarriers for at least three subchannels 441, 442 and 443. Each of the subchannels 441, 442, and 443 includes an upper side loudspeaker and a lower side loudspeaker, as shown in Fig. 1, and also an I channel and a Q channel are allocated thereto. 16, the upper side loudspeaker signal 500 includes one message part 445, which is the first part of the first voice message, and the lower side loudspeakers 510, The second part of the message.

According to the present invention, a voice message, with reference to FIG. 17, comprises two analog frames 430 of an outbound signaling protocol used by the wireless communication system of FIG. 1 and a control frame 330 are shown. The diagram of FIG. 8 shows an example of a frame zero, which is a control frame 330. FIG. Four addresses 501, 502, 503, and 504 and four vectors 518, 521, 522, and 523 that are frame zero are shown. The two addresses 501 and 502 include one selective paging receiver 106 while the other two addresses 503 and 504 are for the second and third selective paging receiver 106. Each address 501, 502, 503, and 504 includes a pointer in each address that points to the protocol location of the associated vector (i. E. And 523, respectively. According to a preferred embodiment of the present invention, the vector position is provided by identifying the number of words 350 following the vector boundary 335 at which the vector begins and the length of the vector by word. It will be appreciated that the relative positions of the address and the vector are independent of each other. The relationship indicated by the pointer is shown by the arrow.

17, the control frame vectors 518, 521, and 523 are uniquely associated with the message portion of one of the subchannels 441 or 442. In the embodiment shown in FIG. In particular, vector 518 points to upper side loudspeakers 500 of subchannel 441, and vector 522 points to lower side lobe 510 of subchannel 442. Similarly, vector 521 refers to both side waves of subchannel 442. That is, for the subchannel 441, the example shows that two different message parts are carried by the upper and lower side lobes. In the case of subchannel 442, two halves of one message portion are carried by the upper and lower side lobes, respectively. As such, the control frame vectors 518, 521, and 523 are information that indicates which subchannel (i. E., What radio frequency) should be referenced for the voice frame message and also that two separate messages from the subchannel Or information indicating whether the first and second halves of a single message are to be restored.

According to a signaling protocol, a method for transmitting first and second messages to an addressable receiver in accordance with the present invention includes receiving first and second messages in a first and a second message, respectively, to generate first and second orthogonal modulation components, Modulating the quadrature components in quadrature; A protocol including synchronization information suitable for triggering an addressable receiver to enter a mode suitable for simultaneously demodulating first and second orthogonal modulation components at a specific time instant according to address information and synchronization information corresponding to an address of an addressable receiver, And transmitting the first and second orthogonal modulation components simultaneously.

One method for two different messages is to transmit them simultaneously through the upper and lower side lobes (or I or Q channels), where one message is a direct voice paging message and the other is a voice mail Box message.

18, the selective paging receiver 106 includes an antenna 840, a quadrature amplitude (QAM) demodulator 850, an FM demodulator 860, a decoder / controller 870, an audio amplifier 872, a speaker An alarm 874, an alarm 876, a display 878, and a control unit 880. [ QAM demodulator 850 performs QAM demodulation on the signal detected by antenna 840 to recover the voice message. FM demodulator 860 performs FM demodulator data and other non-analog data. The output of the FM demodulator 860 is a data limited signal (digital data) coupled to the decoder / controller 870 and is decoded by the decoder / controller 870 to display or store the data message, And signaling protocol information that responds to activate subroutine to demodulate signal 876 by activating alarm 876.

The voice message is recovered through a series of processing modules operating on the I and Q channel outputs of QAM demodulator 850. [ The processing modules are shown as 900 to 960 and are implemented, for example, by software on a digital signal processor or by software stored in the decoder / controller 870. In the latter case, the processing module will be performed by the decoder / controller 870.

If the message portion is modulated with I and Q components, the message portion is recovered directly from the output of QAM demodulator 850. [ If any or all of the messages have been time-reversed in transmission, then the restored message portions are reversed again by the time reversal modules 900 and 910 to the proper sequence. As a result, the message portion S1 (n) is taken at the output of the time reversal module 900 and the message portion S2 (n) is taken at the output of the time reversal module 910. [

On the other hand, if the message portion is modulated with the upper and lower side waves, then the I component passes through the delay module 920 and the Q component passes through the Hilbert transform module 930. The summer module 940 adds the outputs of the modules 920 and 930 and the summer module 950 subtracts the output of the module 930 from the output of the delay module 920. The recovered message portion passes through the time reversal modules 900 and 910 if the time reversal occurs during transmission.

The message parts Sa (n) and Sb (n) are processed by a time sequencing summer 960 that temporally combines the message parts Sa (n) and Sb (n) to reconstruct the original message S .

The attendant function of time demodulation and amplitude modulation is preferably performed to undo such a process performed during modulation. Thus, although not shown in detail in FIG. 18, the time demodulation and amplitude demodulation module is coupled to the output of, for example, time sequencing summer 960. Other post-demodulation processing suitable for increasing the quality of the recovered signal may be assumed in accordance with the present invention.

The description is illustrative only and is not intended to limit the invention in any way whatsoever except as set forth in the following claims.

Claims (19)

A method for transmitting a message to a receiver, Temporally splitting the message into first and second message portions; Orthogonally modulating the first and second quadrature components with the first and second message portions, respectively, to produce first and second quadrature modulation components; And Transmitting the first and second orthogonal modulation components simultaneously ≪ / RTI > The method according to claim 1, Wherein the quadrature modulating comprises generating an in-phase component and a quadrature component, wherein the in-phase component is modulated by the first message portion and the quadrature component is modulated by the second message portion Gt; modulated. ≪ / RTI > The method according to claim 1, Characterized in that the orthogonal modulation step comprises generating upper and lower side lending waves, wherein the upper side lending wave is modulated by the first message part and the lower side lending wave is modulated by the second message part Way. The method according to claim 1, RTI ID = 0.0 > 1, < / RTI > wherein the first and second message portions comprise a single voice message. The method according to claim 1, Further comprising filtering the first and second message portions to substantially eliminate frequencies out of the normal voice spectrum. The method according to claim 1, Further comprising time reversing at least one of the first and second message portions prior to the orthogonal modulation step. The method according to claim 6, Wherein the time reversal step is performed on a frame based on a frame of a signaling protocol according to a pre-ordered sequence. The method according to claim 1, Further comprising compressing the first and second message portions prior to the orthogonal modulation step. The method according to claim 1, Further comprising amplitude companding the first and second message portions prior to the orthogonal modulation step. A transmitter for transmitting a message to a receiver, A speech divider for temporally splitting the message into first and second message portions; An orthogonal modulator for orthogonally modulating the first and second quadrature components with the first and second message portions, respectively, to generate first and second quadrature modulation components; And A transmitter for simultaneously transmitting the first and second orthogonal modulation components onto a carrier signal, And a transmitter. 11. The method of claim 10, The transmitter circuitry triggers the addressable receiver to enter addressing information corresponding to an address of the addressable receiver and a mode suitable for simultaneously demodulating the first and second orthogonal modulation components at a moment in time according to synchronization information, Wherein the transmitter transmits the first and second orthogonal modulation components to a protocol that includes synchronization information suitable for the first and second orthogonal modulation components. 11. The method of claim 10, Wherein the quadrature modulator generates an in-phase component and a quadrature component, the in-phase component is modulated by the first message, and the quadrature component is modulated by the second message. 11. The method of claim 10, Wherein the orthogonal modulator generates upper and lower side loudspeakers, the upper side loudspeaker is modulated by the first message, and the lower side loudspeak is modulated by the second message. 11. The method of claim 10, Further comprising a time reversal circuit for time reversing at least one of the first and second messages. A receiver for receiving a transmission signal including first and second orthogonal modulation components, A demodulator circuit for demodulating the transmit signal to obtain first and second message portions, respectively, from the first and second orthogonal modulation components; And A time sequencer for temporally sequencing the first and second message portions to generate a single message comprised of the first and second message portions, ≪ / RTI > 16. The method of claim 15, Further comprising a time reversal circuit for time reversing at least one of the first and second message portions. 16. The method of claim 15, Wherein the demodulator circuit recovers the first and second message portions from the in-phase component and the quadrature component, respectively. 16. The method of claim 15, Wherein the demodulator circuit recovers the first and second messages from each of the upper and lower side lobes. 16. The method of claim 15, A memory circuit coupled to the memory for decoding address information and synchronization information in response to a correlation of address information from the transmission signal and an address stored in the memory circuit, Further comprising a decoder / controller circuit for triggering the demodulator circuit to simultaneously demodulate the first and second quadrature modulation components at a moment.